Translucent recording medium



Sept. 12, 195o J. B. WALKER 2,522,018 l TRANSLUCENT RECORDING MEDIUM Filed Feb. 5, 1945 f/f/,f//H/ INVENToR.

,4free/vars Patented Sept. 12, 1950 TED STAT Es PATENT oFF-ICE T'TRANSLUEEN T RECORDING MEDIUM .ioseph-..wa1ker, Hollywood, Calif. -:ApplicationFebruary 3, 194`5,-'Serial No.'- 575,983

, a5 ,Claims '.zFIFhis zinventionrelates tov'recording` medial -on ,which-.frmayx be regis-teredgwby"` the; novel: :method 'l'.iereof; ai.-soundopa`ttern. characterized :by varia- .tions in@translucencyl Othemedia corresponding .to thezfdepth or' thickness: ofi' translucent rmaterialrzcomprising"fthe. sound-record reproduction ,being-effected byifmeans actuated in. response: .to :the variable fintensity `ofiza' beam'fof light' -.trans-- mittedby the media to create electrical `iimpulses of4 yrelative :frequencypperiod and` amplitudecorresponding ntol-the'sound pattern.

It is commonf practice' in: the prior to: rimpress aA sound'- record upon-5a 'disk =orf 'taper comypose'dfof -plastic orro'ther:impressionable: substance by means xoil a vstylus connected tof afidiaphragm andadaptedto be lribrate'd against 'fthewplastic in responsey tosound-impurlsee soas to `producean indented 'pattern correspondingtd 'the sound -pattern: activating'thediaphragm. As is well known, 4reproduction of-such arecord is'e'ffected by similar wf'apparatus;Y if e.; ythelsound r'ecord =is moved against-'the l'stylus which' =is= activated by the surliacecontour ofthe record? to reproduce the vibrations lof? 'ther i'diaphragm--and 'accordingly- 'the original sounds of the record. Howeven'in such soundfreprodu'cingsystems 'the friction off-the stylus produces 1 a f sound audible -in f the f loud speaker, vwhich'`-inter-feres -withfdistinct audition. This' is particularly'objectionable A"during" reproduction:fof'fsoundswof `low frequency or volume. Fidelity in Areproduction v'is also affected by-` ithe diculty of maintaining a uniformv pressureof the stylus -fonthe )indented f lsound track, 'the sharper vibrationsfof- 'the stylus,'inc`iden't to sudden changes in vlumeior -trequency,a'ccordingly being magnied A1to1 ra-*certain' extent. Similar-ly, slightizariationsinfthe Aindented track; .indicative of; corresponding` changes fin sound recordeda'are not ffaithfullyfftransposedffdue to inertia; of4 the diaphragm :and: stylus.

i It isfa generalbbjectfof the, present invention to obviate the aboveenoted ..andothen disadvan tages l encounteredim the iprior, var.t.means i, and methods, bytheiprovision yof translucent recordingmedia, comprising .abase ycoated ,with` animpressionable substance inwhich an indented rec.- ord. is formed; 'the translucency of Ithe recording media being variable with theldepth oftheindentation othe'impressedl lpattern whereby variations" Ain' the Vintensity of :light directedbtherethrough-may be utilized Vto activate *s ound reproducing` equipment. i

More specifically, an-object isr to provide-'a Jtape of"substantiallytransparentmaterialbearing two or'more layersofd-ye substances, the upper layerv being blackforof afco1orfwhich;fwhen used with an: :appropriate lter, isopaque, f and theqother layerorlayers being translucent to a degree propoctionate withf their thicknesses.

Anotherzobject isa provision of` a colored sound track-:upon a 4tape or the ..like,idistinguished =by :its embodimentof aisoundipattern indepth or thicknessfof. a colored substance ona transparent base, whereby a lcorresponding pattern vin translucency is provided, enabling the reproduction of. the sound :by the; intensity ofilightyalues which it variably. transmits.

Stilllanotherobject is ythe provision of ay method oiuproducingv a sound record: comprising a Atraneposition of the characteristics .oifthe individual sound impulses into corresponding variations in translucency: ois a. .recording-medium byk varying the thickness lof the sounditrackion Athe medium.

r Uther: iobfjects g and corresponding advantages, such :for examplezas greaterliidelityin reproduction, simplicity'of construction ofthe equipment required, facility in use, and adaptability x to greater .tolerances in the recorded impressionszof sound patterns iin translucenty vvalues than here" tofore .possible,.willbe apparent to thosefofskill inzthe art viupon l an examination' of the following description read .in `the light or :the i accompanying fdrawings ein; vwhich ifEig.;-1= is la diagrammatic rview oil the equipment:- irequiredf for` recordation, and :illustrating its ,use nipona :tape: ,recordingwmedium, shown,

partially,- inuseotion;

1EEig.:2-is"a broken Sectional View -ofa slightly modiiied-.fform of recording medium;

willig.vv 3,:is, a "longitudinal section ,of another embodiment'fof recording medium;

@Eiga-fris a:diagrammatic View of the reproducingfsunit.

Referring to: the :drawings in detail, `thefnumerals inf which `indicate similarl parts .throughout theseveralfviews, 5-zdesignates generally a tapefon swhichaaisoundirecordis adapted: to. be registered. i [Itl will ibe understood that. while-the recordingmediazof thel embodiments ofmy invention herein rillnstrated and-.described arewin the yforni of tape;.itheir;nove1'features are equally well;.adapted :for embodiment in disk,y cylinder, or eitherform. vil/'here the recording medium consists: of; itape; .it :is carried on reels, being drawn fromffone: ofsxtheazreelsr6 lthrough suitable guide and vsupporting. :means .(not shown) associated withthetrecording:unit by -a -ipower-driven takeup-reel' 1. sTape-`5fis supported', guided, and moved ina'a'ilike -manner .;thro1ieh a: reproducing iunit, ,of a Ttype hereinafter :referred t0,"When reproduction ot1the sound record isfdesired.

gRe'ierring ,particularly to Fig.l 1, the recording asaaova unit, which is preferably magnetic, comprises generally a stylus 8 in combination with means for causing vibration of the stylus in synchronization with sound impulses intended for recordation. To this end, stylus 8 is connected to a diaphragm (not shown) enclosed in a magnetic recording head of a type well known in the art, and generally designated by numeral 9, which is carried on a pin I0, disposed axially transverse to the direction of movement of tape 5, journalled in suitable bearings (not shown), whereby stylus 8 may be tilted into and out of contact with the tape. The sound impulses to be recorded are tr-ansposed into electrical impulses by a microphone II, and are magnified by the amplifier I2 to actuate the magnetically-controlled diaphragm of the recording head 9.

The recording medium 5 comprises, in the embodiment shown in Figs. 1 and 4, a transparent base I3, composed of Celluloid or the like coated with two layers of dyed substances, such as a gelatin compound. It 4will be understood, however, that the base may be composed of a translucent material which is not transparent. It is, however, essential that the upper or surface layer I4 lbe very thin but completely opaque to both visible and infra-red light. Moreover, the surface layer I4 is suiiiciently renitent to resist penetration by stylus 8 when not activated by the diaphragm. The lower layer or underlayer I5 is, however, soft and impressionable, and carries the sound pattern, reproducible by the equipment herein contemplated, which is impressed in the i underlayer I5. Layer I5 is translucent, whereby a registerable difference in degree of translucency results from the successive variations in thickness of the layer incident to impressing the record in accordance with the method hereof.

The sound track is formed in tape 5 by the recording unit incident to lowering stylus 8 into contact with the tape, and initiating, coincidentally, the audition and the rotation of the take-up reel, to move the tape against the stylus. The stylus cuts through the opaque surface I4V in response to vibration of the diaphragm of head 9, and forms an indented pattern in the dyed underlayer I5. As the original thickness of the underlayer l5 is uniform, the indentation of this layer by the stylus varies the thickness of the layer by removing a, minute portion thereof, correspondingly varying the translucency of the track on the line of movement of the stylus, whereby a continuous pattern, correlated with the succession of sound impulses and characterized by penetration of layer I4 and varying thicknesses of the layer I5 is formed on the tape.

The reproducing equipment consists of the reels 6 and 1 and guiding and supporting mechanism (not shown) for carrying tape 5 beneath a mask diaphragm I6, which is provided with a narrow slit I1 for the passage of a beam of light onto the tape. The light ibeam, emanating from a light source I8 is directed through the slit by lenses i9 (shown in dotted lines in Fig. 4.) Mask I6 is supported in a position very close to tape 5 by suitable brackets 20, in order that the light beam is extremely narrow at the surface of the track in layer I5, i. e., with the depth of the indentations produced by stylus 8 in the recording operation, as the tape is moved through the light beam. A filter may be interposed between the tape and photo-electric cell, as indicated at 21, for a purpose hereinafter described. The terminals 22 and 23 of thev cell are connected by wires 24-24 in Va circuit through amplier 25 and loud speaker 25 in a conventional manner, the electrical impulses being transposed into sound vibrations by the speaker.

It will thus be seen that it is essential that the surface layer III be opaque, while the underlayer I5 must be translucent, whereby variations in thickness effected by stylus 8 in forming the sound track produces a corresponding pattern in the translucency of the track. To this end, in the embodiment of Fig. 1 the thin surface layer I4 is composed of an opaque substance, and the underlayer consists of a material idyed a uniform gray. It will be understood that while the underlayer is translucent, in those reaches of the sound track where the impression made by the stylus is slight, the intensity of the light permitted to penetrate the tape will be correspondingly very low, and conversely, where a deep impression is made, the

' resultant thin sound track will offer very little resistance to the passage of the beam of light.

With a tape having a black and gray dyed sound track, a white light may be effectively used for reproduction purposes. However, in a modified form of the invention, the tape is coated with a surface layer of a blue dyed substance and an underlayer of red. Even though both layers are translucent, a filter or a combination of lters, interposed between the tape and photo-electric cell 2|, may be utilized to filter out all light passing through the blue surface layer which would activate the photo-electric cell while passing the clear red beam to the cell. Thus, the blue layer, where it occurs on the sound track, would be in eiect opaque in a reproducing unit incorporating such a filter.

In Fig. 2 I have illustrated a. tape having colored layers of the character last above noted. In this embodiment, however, two translucent underlayers 2B and 29 are provided. The layer 29 immediately below the "opaque surface is a tone of red, for example, while the layer 28 therebelow in contact with the base is a pink tint.

It will be appreciated that the opaque layer Il may be omitted or, if the renitent quality of layer I4 is desired, such layer may be transparent if the full thickness of the underlayer or layers offers sufficient resistance to the passage of the light so as to obviate the reception by the photoelectric cell 2| of light of an intensity to eectively actif vate the latter. Fig. 3 illustrates a preferred emtape. Where the stylus has removed the opaque bodiment of recording media in which the base I3 is provided with a single layer 30 of impressionable substance. This layer may be gray or any single color or a multi-color blend, having an effective light transmission range'from substantial opacity to substantial transparency depending upon the thickness of the portion thereof, toA which the light is directed, i. e., upon the depth of the impression formed incident to the recordation. The combination of a colored coating with a, filter 21 adapted to pass only light of that color has the added advantage of obviating the necessity of a light-tight seal between the photoelectric cell and tape 5, as white or other colored light from external sources would not pass through the filter and, accordingly, would not interfere with faithful transcription of the recorded sound pattern.

In this description and in the claims annexed hereto, the term opaque or opacity, as applied to a coating carried by the tape, will be understood to mean that the path of light is accordingly interrupted either at the surface of the layer referred to or by the filter, and that in any embodiment the color or black dye of the surface layer is effective to block substantially all light from reaching the cell. Many colors other than red or blue in either of the layers may be substituted in specific embodiments of the tape, and the selection of the lter or filters to be employed therewith in the reproducing unit to attain the effect desired Will be within the skill of those in the art. In the following claims the term translucent as applied to the base I3 is used to designate a material capable of transmitting light with or Without diiusion, and accordingly, includes materials which are clearly transparent as well as those through which only certain rays of light will pass. The term translucent as it applies in the following claims to the cutting layer, corresponding to layers l5, 28, 29 or 30 or equivalent thereof, contemplates a material adapted to pass certain rays of light but which prohibits the passage of other rays of light and accordingly the material so identified distinguishes from clearly transparent materials.

What I claim and desire to secure by Letters Patent is:

1. A recording medium, comprising a transparent base and an intermediate layer of translucent material normally of uniform thickness superimposed upon said base, and an opaque surface layer, the degree of translucency of said intermediate layer being variable in response to Variation of the thickness thereof, whereby a sound pattern in translucency of said intermediate layer may be produced by varying the thickness of said last-named layer.

2. A recording medium, comprising a translu cent base, a translucent layer superimposed upon said base, and an opaque layer coating said translucent layer, both of said layers bearing an indented sound track, the depth of the indentations being correlated with the amplitude, period and frequency of the sound impulses recorded, the translucency of the rst-named layer being Variable with the thickness of the sound track to form a pattern in degree of translucency of the layer corresponding to the sound pattern.

3. A recording medium comprising a translucent base, several coatings of an impressionable substance, a sound track in said coatings characterized by an indented pattern corresponding to the sound pattern to be recorded, said coatings being of different blended shades of color, Whereby the sound track Varies in translucency with the depth of the indentations.

4. A recording medium comprising a translu* cent base, a colored coating of an impressionable substance on said base, a second coating of impressionable substance of a different color be tween said base and said first coating, said coatings characterized by an. indented pattern therein corresponding to a sound pattern whereby the sound track varies in translucency With the depth of the indentations and correspond in its variable degree of translucency to said sound pattern.

5. A recording medium comprising a translu cent base, a multi-colored coating of an impressionable substance on said base, on opaque layer superposed upon said coating, said coating having a sound track therein comprising a reprodu ible pattern in translucency corresponding with an indented pattern formed in said substance, the indentations and corresponding Variations in translucency of the coating being correlated with a sound pattern to be reproduced.

JOSEPH B. WALKER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,707,243 Wildhaber Apr. 2, 1929 1,919,116 Miller July 18. 1933 1,919,117 Miller July 18, 1933 1,956,626 Robbins May 1, 1934 2,005,847 Schmidt June 25, 1935 2,008,092 Biber July 16, 1935v 2,032,741 Dippel Mar. 3, 1936 2,040,693 Huguenard May l2, 1936 2,086,934 Bonneau July 13, 1937 2,093,215 Six Sept. 14, 1937 2,163,087 De Boer June 20, 1939 2,224,170 Van Der Mevlen Dec. 10, 1940 2,273,916 Westerkamp Feb. 24, 1942 

